The present invention relates generally to the field of sterile fluid dispensing devices, and more particularly, is directed to novel delivery and venting devices capable of maintaining sterile conditions within a multi-dose dispensing container.
Sterile solutions are useful for certain medicinal and opthalmic applications in which it is desirable to expel a portion of a sterile liquid from a multi-dose container for treatment purposes while maintaining the integrity of the remaining sterile solution. In such applications, it is necessary either to provide a bacteriostatic agent in the solution itself or to remove microorganisms and other contaminants from the flow of replacement air into the container. It is also necessary to ensure that the fluid dispensing path permits no intrusion of contaminants into the container after dispensing a portion of the sterile solution.
In widely accepted practice, the solution delivery is accomplished by generating sufficient dispensing pressure by squeezing the container and then providing means for replacement air to enter the container. A preservative is employed to permit multi-dose usage.
In one presently employed application, a sterile solution has been developed for daily cleaning and disinfection of contact lenses. Presently available sterile solutions for such use are usually stored in a multi-dose bottle to which a bacteriostatic agent has been added to maintain the sterile integrity of the solution. Due to the physiological characteristics of the users, the bacteriostatic agents added for preservation of sterility frequently cause discomfort and irritation to the eyes after the lenses have been treated with such a preserved solution. In fact, presently available commercial contact lens disinfection solutions supplied in multi-dose containers carry warning labels offering instructions to the user in the event that eye irritation occurs.
In view of the fact that the multi-dose containers presently in use must include a preservative to maintain the sterility of the solution, and because of the eye irritation that frequently occurs, other workers in the art have developed single service containers which remain sealed until use. In this way a non-preserved, sterile, lens solution is dispensed which contains no bacteriostatic agent and thus no irritant is transmitted to the eye of the user. While such single service containers are useful to accomplish the desired purpose, the very fact that a small container must be developed and manufactured for only one time use adds a considerable increase in cost to the single treatment application. Due to the high cost of a single service container when compared to the cost of a multi-dose package, the need remains to provide a multi-dose container capable of maintaining a sterile solution without requiring the addition of a bacteriostatic agent. The present invention is addressed to the solution of this problem.